81209109 has 8 divisors (see below), whose sum is σ = 109583712. Its totient is φ = 53486960.

The previous prime is 81209101. The next prime is 81209111. The reversal of 81209109 is 90190218.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81209109 - 2³ = 81209101 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81209101) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 162822 + ... + 163319.

It is an arithmetic number, because the mean of its divisors is an integer number (13697964).

Almost surely, 2^81209109 is an apocalyptic number.

It is an amenable number.

81209109 is a deficient number, since it is larger than the sum of its proper divisors (28374603).

81209109 is a wasteful number, since it uses less digits than its factorization.

81209109 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 326227.

The product of its (nonzero) digits is 1296, while the sum is 30.

The square root of 81209109 is about 9011.6096786312. The cubic root of 81209109 is about 433.0468812302.

It can be divided in two parts, 81209 and 109, that added together give a palindrome (81318).

The spelling of 81209109 in words is "eighty-one million, two hundred nine thousand, one hundred nine".